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Need assistance with this error: Syntax error, command unrecognized. The server response was: 4.3.21 Mailbox server busy, mail intentionally delayed

Anonymous
2022-02-14T17:24:52+00:00

Using SendGrip to send several emails and most are successful, but then some are not successful and this is the error message: Syntax error, command unrecognized. The server response was: 4.3.21 Mailbox server busy, mail intentionally delayed. Unable to find any relevent information on this error in Microsoft community.

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  1. Anonymous
    2022-02-14T17:48:20+00:00

    Hi AJJLV,

    Thank you for posting into the forum community. We will highly appreciated your kind cooperation and patience in our forum community.

    Based on your mentioned description and error message, if you are using Microsoft 365 Exchange Online mailbox account, please kindly refer to this detailed information article about Remote Server returned 554 4.3.2 mailbox busy when you send mail to a mailbox in Exchange Online

    If the issue persist, I have shared such information via private message https://answers.microsoft.com/en-us/privatemessage/inbox. Please access this ULR link.

    Regards,

    Darpan

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